Disclaimer: this post is mainly based on my professional experience of a litigation lawyer in Russia. Things may be very different in U.S. and in Europe. (I hope they are.)

The part I'm less comfortable with is

Patents will no longer be assumed to be valid by courts. The aggressor has to argue its case that the patent is valid. [...] In other words, the burden of proof shifts from defendant to aggressor.

This is somehow problematic. There is such concept in the science of Law, which we call "reallocation of burden of proof" ("перераспределение бремени доказвания" in Russian). This means that in cases when (1) the law demands that someone has to prove that something is right or valid and (2) the possible range of evidence in support of righteousness and validity isn't naturally finite, in court the burden of proofs switches to the opposite side, which has to prove that the thing in question is wrong or invalid. The validness of patent follows from the novelty, unobviousness and practical applicability of the invention. Of these three only the practical applicability can really be proved with a finite amount of pieces of evidence; novelty and obviousness can only be claimed (expert opinion is required, but is it a problem for an "aggressive corporation"?). In fact, the validness of patent largely depends on the existence of the prior art; keeping in mind that non-existence can't be really proved at all, the burden of proof in patent cases is deemed to rest on defendant.